Remove RetainPtrObjectHash and RetainPtrObjectHashTraits
Remove RetainPtrObjectHash and RetainPtrObjectHashTraits

RetainPtrObjectHash and RetainPtrObjectHashTraits classes are used in Safari and not used anywhere
in Blink or Chromium, so they should be removed from Blink WTF.

Review URL: https://chromiumcodereview.appspot.com/14698008

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@150039 bbb929c8-8fbe-4397-9dbb-9b2b20218538

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk